Hepatitis B virus induces cell proliferation via HBx-induced microRNA-21 in hepatocellular carcinoma by targeting programmed cell death protein4 (PDCD4) and phosphatase and tensin homologue (PTEN). PLoS One. 2014;9:e91745. [PMID: 24633222 PMCID: PMC3954734 DOI: 10.1371/journal.pone.0091745]

Strain Variation Can Significantly Modulate the miRNA Response to Zika Virus Infection

Zika virus (ZIKV) is a mosquito-transmitted virus that has emerged as a major public health concern due to its association with neurological disorders in humans, including microcephaly in fetuses. ZIKV infection has been shown to alter the miRNA profile in host cells, and these changes can contain elements that are proviral, while others can be antiviral in action. In this study, the expression of 22 miRNAs in human A549 cells infected with two different ZIKV isolates was investigated. All of the investigated miRNAs showed significant changes in expression at at least one time point examined. Markedly, 18 of the miRNAs examined showed statistically significant differences in expression between the two strains examined. Four miRNAs (miR-21, miR-34a, miR-128 and miR-155) were subsequently selected for further investigation. These four miRNAs were shown to modulate antiviral effects against ZIKV, as downregulation of their expression through anti-miRNA oligonucleotides resulted in increased virus production, whereas their overexpression through miRNA mimics reduced virus production. However, statistically significant changes were again seen when comparing the two strains investigated. Lastly, candidate targets of the miRNAs miR-34a and miR-128 were examined at the level of the mRNA and protein. HSP70 was identified as a target of miR-34a, but, again, the effects were strain type-specific. The two ZIKV strains used in this study differ by only nine amino acids, and the results highlight that consideration must be given to strain type variation when examining the roles of miRNAs in ZIKV, and probably other virus infections.

Exploring the Microbiome in Gastric Cancer: Assessing Potential Implications and Contextualizing Microorganisms beyond H. pylori and Epstein-Barr Virus

While previous research has primarily focused on the impact of H. pylori and Epstein-Barr virus (EBV), emerging evidence suggests that other microbial influences, including viral and fungal infections, may also contribute to gastric cancer (GC) development. The intricate interactions between these microbes and the host's immune response provide a more comprehensive understanding of gastric cancer pathogenesis, diagnosis, and treatment. The review highlights the roles of established players such as H. pylori and EBV and the potential impacts of gut bacteria, mainly Lactobacillus, Streptococcus, hepatitis B virus, hepatitis C virus, and fungi such as Candida albicans. Advanced sequencing technologies offer unprecedented insights into the complexities of the gastric microbiome, from microbial diversity to potential diagnostic applications. Furthermore, the review highlights the potential for advanced GC diagnosis and therapies through a better understanding of the gut microbiome.

The Complex Role of HBeAg and Its Precursors in the Pathway to Hepatocellular Carcinoma

Hepatitis B virus (HBV) is one of the seven known human oncogenic viruses and has adapted to coexist with a single host for prolonged periods, requiring continuous manipulation of immunity and cell fate decisions. The persistence of HBV infection is associated with the pathogenesis of hepatocellular carcinoma, and various HBV proteins have been implicated in promoting this persistence. The precursor of hepatitis e antigen (HBeAg), is translated from the precore/core region and is post-translationally modified to yield HBeAg, which is secreted in the serum. HBeAg is a non-particulate protein of HBV and can act as both a tolerogen and an immunogen. HBeAg can protect hepatocytes from apoptosis by interfering with host signalling pathways and acting as a decoy to the immune response. By evading the immune response and interfering with apoptosis, HBeAg has the potential to contribute to the hepatocarcinogenic potential of HBV. In particular, this review summarises the various signalling pathways through which HBeAg and its precursors can promote hepatocarcinogenesis via the various hallmarks of cancer.

Hepatitis B Virus X Protein Inhibits the Expression of Barrier To Autointegration factor1 via Upregulating miR-203 Expression in Hepatic Cells

Hepatitis B virus (HBV) infection targets host restriction factors that inhibit its replication and survival. Previous studies have shown that barriers to autointegration factor1 (BANF1) inhibited the replication of herpes simplex virus and vaccinia virus by binding to phosphate backbone of dsDNA. To date, no reports are available for the interplay between BANF1 and HBV. In this study, we elucidated the mechanisms by which HBV inhibit BANF1. First, the effect of HBV on BANF1 was observed in Huh-7, Hep G2, and Hep G2.2.15 cells. Huh-7 cells were transfected with pHBV_1.3 or HBx plasmids. The results showed that there was a decreased expression of BANF1 in Hep G2.2.15 cells (P ≤ 0.005) or in HBV/HBx expressing Huh-7 cells (P ≤ 0.005), whereas BANF1 overexpression decreased viral replication (P ≤ 0.05). To study whether phosphorylation/dephosphorylation of BANF1 was responsible for antiviral activity, mutants were created, and it was found that inhibition due to mutants was less significant compared to BANF1 wild type. Previous studies have shown that HBV, at least in part, could regulate the expression of host miRNAs via HBx. It was found that miR-203 expression was high in Hep G2.2.15 cells (P ≤ 0.005) compared to Hep G2 cells. Next, the effect of HBx on miR-203 expression was studied and result showed that HBx upregulated miR-203 expression (P ≤ 0.005). Overexpression of miR-203 downregulated BANF1 expression (P ≤ 0.05) and viral titer was upregulated (P ≤ 0.05), while inhibition of miR-203, reversed these changes. In conclusion, BANF1 downregulated HBV, whereas HBV inhibited BANF1, at least in part, via HBx-mediated miR-203 upregulation in hepatic cells. IMPORTANCE In this study, for the first time, we found that BANF1 inhibited HBV replication and restricted the viral load. However, as previously reported for other viruses, the results in this study showed that BAF1 phosphorylation/dephosphorylation is not involved in its antiviral activity against HBV. HBV infection inhibited the intracellular expression of BANF1, via HBx-mediated upregulation of miR-203 expression. Overexpression of miR-203 downregulated BANF1 and increased the viral titer, while inhibition of miR-203 reversed these changes. This study helped us to understand the molecular mechanisms by which HBV survives and replicates in the host cells.

DNA methyltransferase 1 knockdown reverses PTEN and VDR by mediating demethylation of promoter and protects against renal injuries in hepatitis B virus-associated glomerulonephritis

Background

Aberrant DNA methylation patterns, including hypermethylation of key genes that inhibit fibrosis and inflammation, have been described in human kidney diseases. However, the role of DNA methyltransferase 1 (DNMT1) in hepatitis B virus-associated glomerulonephritis (HBV-GN) remains unclear.

Methods

We explored the underlying mechanism by establishing HBV X protein (HBx) overexpressing renal tubular epithelial (HK-2) cells and human podocytes with DNMT1 knockdown. Using RNA-sequencing to determine the downstream targets of DNMT1 and evaluate its levels of promoter methylation. HBV transgenic mice were used to examine the effects of DNMT1 inhibitor on renal in vivo.

Results

DNMT1 was significantly upregulated in the renal tissue of HBV-GN patients, accompanied by injuries of HK-2 cells and podocytes. HBx markedly upregulated DNMT1 and induced epithelial-mesenchymal transition (EMT) and inflammation in HK-2 cells and human podocytes. This increased DNMT1 expression was attenuated after DNMT1 knockdown, accompanied by restored HK-2 cells and podocyte injuries resulting from the activation of PI3K/Akt/mTOR and nuclear factor-kappa B (NF-κB) pathways. Hypermethylation of the phosphatase and tensin homolog (PTEN) promoter and vitamin D receptor (VDR) was induced in HBx-overexpressing HK-2 cells and podocytes, respectively, whereas DNMT1 knockdown effectively corrected these alterations. Furthermore, PTEN and VDR ablation resulted in marked EMT and inflammation induction in HBx-overexpressing HK-2 cells and human podocytes even with DNMT1 knockdown. Downregulation of the PI3K/Akt/mTOR-related pathway attenuated HBx-induced EMT and inflammation in HK-2 cells. Luciferase reporter assay revealed VDR as a direct target of the Snail family transcriptional repressor 1 (SNAI1) in HBx-overexpressing podocytes. DNA methylation inhibitor 5-azacytidine alleviated urinary protein and renal inflammation in HBV transgenic mice via PTEN-PI3K/Akt signaling and VDR signaling axis.

Conclusions

Our study clarifies the potential epigenetic mechanisms underlying HBx-induced renal injuries in HBV-GN and the renoprotective effects of inhibiting DNMT1, which can provide important insights into the development of treatments for HBV-GN.

Micro-Players of Great Significance-Host microRNA Signature in Viral Infections in Humans and Animals

Over time, more and more is becoming known about micro-players of great significance. This is particularly the case for microRNAs (miRNAs; miR), which have been found to participate in the regulation of many physiological and pathological processes in both humans and animals. One such process is viral infection in humans and animals, in which the host miRNAs—alone or in conjunction with the virus—interact on two levels: viruses may regulate the host’s miRNAs to evade its immune system, while the host miRNAs can play anti- or pro-viral roles. The purpose of this comprehensive review is to present the key miRNAs involved in viral infections in humans and animals. We summarize the data in the available literature, indicating that the signature miRNAs in human viral infections mainly include 12 miRNAs (i.e., miR-155, miR-223, miR-146a, miR-122, miR-125b, miR-132, miR-34a, miR -21, miR-16, miR-181 family, let-7 family, and miR-10a), while 10 miRNAs are commonly found in animals (i.e., miR-155, miR-223, miR-146a, miR-145, miR-21, miR-15a/miR-16 cluster, miR-181 family, let-7 family, and miR-122) in this context. Knowledge of which miRNAs are involved in different viral infections and the biological functions that they play can help in understanding the pathogenesis of viral diseases, facilitating the future development of therapeutic agents for both humans and animals.

Integrated Analysis of the Altered lncRNA, microRNA, and mRNA Expression in HBV-Positive Hepatocellular Carcinoma

Hepatitis B virus (HBV) infection is the most prominent risk factor for developing hepatocellular carcinoma (HCC), which can increase the incidence of HCC by more than 100 times. Accumulated evidence has revealed that non-coding RNAs (ncRNAs) play a regulatory role in various tumors through the long non-coding RNA (lncRNA)–microRNA (miRNA)–mRNA regulation axis. However, the involvement of the ncRNA regulatory network in the progression of HBV infection-induced HCC remains elusive. In the current work, five tumor samples from patients with hepatitis B surface antigen (HBsAg)-positive HCC and three tumor samples from patients with HBsAg-negative HCC were collected for whole-transcriptome sequencing. Between the two groups, 841 lncRNAs, 54 miRNAs, and 1118 mRNAs were identified to be differentially expressed (DE). The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that DE genes were mainly involved in cancer-related pathways, including Wnt and MAPK signaling pathways. The Gene Expression Omnibus (GEO) analysis further validated the selected DE mRNAs. The DE lncRNA–miRNA–mRNA network was built to explore the effect of HBV infection on the regulation of ncRNAs in HCC. These findings provide novel insights into the role of HBV infection in the progression of HCC.

Hyaluronan-mediated motility receptor antisense RNA 1 promotes hepatitis B virus-related hepatocellular carcinoma progression by regulating miR-627-3p/High Mobility Group AT-hook 2 axis

Hepatocellular carcinoma (HCC) is a common malignancy in the world, with high mortality and poor prognosis. Hepatitis B virus (HBV) is one of the key factors implicated in the occurrence of HCC. Increasing evidence suggests that miRNAs play important roles in the development and metastasis of HBV-associated HCC (HBV-HCC). Here, we performed CCK8 (Cell count kit-8), EdU (5-ethynyl-2’-deoxyuridine) incorporation assay, wound-healing assay, transwell assay to study the changes in the cellular phenotype. Luciferase reporter assay, RNA pull-down experiment, RT-qPCR and western blotting were employed to study molecular mechanism. In addition, we also constructed a mouse HCC xenograft model to verify the functional role of HMMR-AS1/miR-627-3p/HMGA2 signal axis in vivo. Our study demonstrated that HMMR-AS1 was highly expressed in HCC tissues and cell lines, suggesting its implication in the progression of HCC. In addition, in vitro experiments showed that high HMMR-AS1 expression facilitated the migration, invasion, and proliferation of HCC cells. We further revealed that HMMR-AS1 promoted the malignant phenotype of HCC cells by regulating miR-627-3p/HMGA2 axis. Together, our data suggest that HMMR-AS1 regulates HBV-HCC progression via miR-627-3p/HMGA2 axis.

Molecular pathways in viral hepatitis-associated liver carcinogenesis: An update

Hepatocellular carcinoma (HCC) is the most common type of cancer among primary malignant tumors of the liver and is a consequential cause of cancer-related deaths worldwide. In recent years, uncovering the molecular mechanisms involved in the development and behavior of this tumor has led to the identification of multiple potential treatment targets. Despite the vast amount of data on this topic, HCC remains a challenging tumor to treat due to its aggressive behavior and complex molecular profile. Therefore, the number of studies aiming to elucidate the mechanisms involved in both carcinogenesis and tumor progression in HCC continues to increase. In this context, the close association of HCC with viral hepatitis has led to numerous studies focusing on the direct or indirect involvement of viruses in the mechanisms contributing to tumor development and behavior. In line with these efforts, this review was undertaken to highlight the current understanding of the molecular mechanisms by which hepatitis B virus (HBV) and hepatitis C virus (HCV) participate in oncogenesis and tumor progression in HCC and summarize new findings. Cumulative evidence indicates that HBV DNA integration promotes genomic instability, resulting in the overexpression of genes related to cancer development, metastasis, and angiogenesis or inactivation of tumor suppressor genes. In addition, genetic variations in HBV itself, especially preS2 deletions, may play a role in malignant transformation. Epigenetic dysregulation caused by both viruses might also contribute to tumor formation and metastasis by modifying the methylation of DNA and histones or altering the expression of microRNAs. Similarly, viral proteins of both HBV and HCV can affect pathways that are important anticancer targets. The effects of these two viruses on the Hippo-Yap-Taz pathway in HCC development and behavior need to be investigated. Additional, comprehensive studies are also needed to determine these viruses' interaction with integrins, farnesoid X, and the apelin system in malignant transformation and tumor progression. Although the relationship of persistent inflammation caused by HBV and HCV hepatitis with carcinogenesis is well defined, further studies are warranted to decipher the relationship among inflammasomes and viruses in carcinogenesis and elucidate the role of virus-microbiota interactions in HCC development and progression.

Oncogenic viruses and chemoresistance: What do we know?

Chemoresistance is often referred to as a major leading reason for cancer therapy failure, causing cancer relapse and further metastasis. As a result, an urgent need has been raised to reach a full comprehension of chemoresistance-associated molecular pathways, thereby designing new therapy methods. Many of metastatic tumor masses are found to be related with a viral cause. Although combined therapy is perceived as the model role therapy in such cases, chemoresistant features, which is more common in viral carcinogenesis, often get into way of this kind of therapy, minimizing the chance of survival. Some investigations indicate that the infecting virus dominates other leading factors, i.e., genetic alternations and tumor microenvironment, in development of cancer cell chemoresistance. Herein, we have gathered the available evidence on the mechanisms under which oncogenic viruses cause drug-resistance in chemotherapy.

Potential of HBx Gene for Hepatocarcinogenesis in Noncirrhotic Liver

Current treatments for hepatitis B virus (HBV) using nucleos(t)ide analogs cannot eliminate the risk of hepatocellular carcinoma (HCC) development. As HBV-associated HCC can develop even in the absence of liver cirrhosis, HBV is regarded to possess direct oncogenic potential. HBV regulatory protein X (HBx) has been identified as a primary mediator of HBV-mediated hepatocarcinogenesis. A fragment of the HBV genome that contains the coding region of HBx is commonly integrated into the host genome, resulting in the production of aberrant proteins and subsequent hepatocarcinogenesis. Besides, HBx interferes with the host DNA or deoxyribonucleic acid damage repair pathways, signal transduction, epigenetic regulation of gene expression, and cancer immunity, thereby promoting carcinogenesis in the noncirrhotic liver. However, numerous molecules and pathways have been implicated in the development of HBx-associated HCC, suggesting that the mechanisms underlying HBx-mediated hepatocarcinogenesis remain to be elucidated.

Host Epigenetic Alterations and Hepatitis B Virus-Associated Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most frequent primary malignancy of the liver and a leading cause of cancer-related deaths worldwide. Although much progress has been made in HCC drug development in recent years, treatment options remain limited. The major cause of HCC is chronic hepatitis B virus (HBV) infection. Despite the existence of a vaccine, more than 250 million individuals are chronically infected by HBV. Current antiviral therapies can repress viral replication but to date there is no cure for chronic hepatitis B. Of note, inhibition of viral replication reduces but does not eliminate the risk of HCC development. HBV contributes to liver carcinogenesis by direct and indirect effects. This review summarizes the current knowledge of HBV-induced host epigenetic alterations and their association with HCC, with an emphasis on the interactions between HBV proteins and the host cell epigenetic machinery leading to modulation of gene expression.

Cell death pathways and viruses: Role of microRNAs

Viral infections lead to the death of more than a million people each year around the world, both directly and indirectly. Viruses interfere with many cell functions, particularly critical pathways for cell death, by affecting various intracellular mediators. MicroRNAs (miRNAs) are a major example of these mediators because they are involved in many (if not most) cellular mechanisms. Virus-regulated miRNAs have been implicated in three cell death pathways, namely, apoptosis, autophagy, and anoikis. Several molecules (e.g., BECN1 and B cell lymphoma 2 [BCL2] family members) are involved in both apoptosis and autophagy, while activation of anoikis leads to cell death similar to apoptosis. These mechanistic similarities suggest that common regulators, including some miRNAs (e.g., miR-21 and miR-192), are involved in different cell death pathways. Because the balance between cell proliferation and cell death is pivotal to the homeostasis of the human body, miRNAs that regulate cell death pathways have drawn much attention from researchers. miR-21 is regulated by several viruses and can affect both apoptosis and anoikis via modulating various targets, such as PDCD4, PTEN, interleukin (IL)-12, Maspin, and Fas-L. miR-34 can be downregulated by viral infection and has different effects on apoptosis, depending on the type of virus and/or host cell. The present review summarizes the existing knowledge on virus-regulated miRNAs involved in the modulation of cell death pathways. Understanding the mechanisms for virus-mediated regulation of cell death pathways could provide valuable information to improve the diagnosis and treatment of many viral diseases.

Mechanisms of Hepatitis B Virus-Induced Hepatocarcinogenesis

Hepatitis B virus (HBV) is a major cause of hepatocellular carcinoma (HCC). There are approximately 250 million people in the world that are chronically infected by this virus, resulting in nearly 1 million deaths every year. Many of these patients die from severe liver diseases, including HCC. HBV may induce HCC through the induction of chronic liver inflammation, which can cause oxidative stress and DNA damage. However, many studies also indicated that HBV could induce HCC via the alteration of hepatocellular physiology that may involve genetic and epigenetic changes of the host DNA, the alteration of cellular signaling pathways, and the inhibition of DNA repair mechanisms. This alteration of cellular physiology can lead to the accumulation of DNA damages and the promotion of cell cycles and predispose hepatocytes to oncogenic transformation.

miRNAs as Potential Biomarkers for Viral Hepatitis B and C

Around 257 million people are living with hepatitis B virus (HBV) chronic infection and 71 million with hepatitis C virus (HCV) chronic infection. Both HBV and HCV infections can lead to liver complications such as cirrhosis and hepatocellular carcinoma (HCC). To take care of these chronically infected patients, one strategy is to diagnose the early stage of fibrosis in order to treat them as soon as possible to decrease the risk of HCC development. microRNAs (or miRNAs) are small non-coding RNAs which regulate many cellular processes in metazoans. Their expressions were frequently modulated by up- or down-regulation during fibrosis progression. In the serum of patients with HBV chronic infection (CHB), miR-122 and miR-185 expressions are increased, while miR-29, -143, -21 and miR-223 expressions are decreased during fibrosis progression. In the serum of patients with HCV chronic infection (CHC), miR-143 and miR-223 expressions are increased, while miR-122 expression is decreased during fibrosis progression. This review aims to summarize current knowledge of principal miRNAs modulation involved in fibrosis progression during chronic hepatitis B/C infections. Furthermore, we also discuss the potential use of miRNAs as non-invasive biomarkers to diagnose fibrosis with the intention of prioritizing patients with advanced fibrosis for treatment and surveillance.

microRNAs in inflammatory alveolar bone defect: A review

Inflammatory alveolar bone defects are caused by periodontal pathogens, are one of the most common oral diseases in the clinic, and are characterized by periodontal support tissue damage. MicroRNAs (miRNAs) can participate in a variety of inflammatory lesions and modulate bone metabolism through the posttranscriptional regulation of target genes. In recent years, studies have confirmed that some miRNAs play significant roles in the development of inflammatory alveolar bone defects. Therefore, we reviewed the correlation between miRNAs and inflammatory alveolar bone defects and elucidated the underlying mechanisms to provide new ideas for the prevention and treatment of inflammatory alveolar bone defects.

The Multiple Roles of Hepatitis B Virus X Protein (HBx) Dysregulated MicroRNA in Hepatitis B Virus-Associated Hepatocellular Carcinoma (HBV-HCC) and Immune Pathways

Currently, the treatment of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) [HBV-HCC] relies on blunt tools that are unable to offer effective therapy for later stage pathogenesis. The potential of miRNA to treat HBV-HCC offer a more targeted approach to managing this lethal carcinoma; however, the complexity of miRNA as an ancillary regulator of the immune system remains poorly understood. This review examines the overlapping roles of HBx-dysregulated miRNA in HBV-HCC and immune pathways and seeks to demonstrate that specific miRNA response in immune cells is not independent of their expression in hepatocytes. This interplay between the two pathways may provide us with the possibility of using candidate miRNA to manipulate this interaction as a potential therapeutic option.

[Pregnane X receptor promotes programmed cell death protein 4 expression in HepG2 cells]

OBJECTIVE

To investigate the role of pregnane X receptor (PXR) in the regulation of programmed cell death proteins (PDCDs) in HepG2 cells and explore the underlying molecular mechanism.

METHODS

HepG2 cells were treated with PXR agonist rifampicin (10 μmol/L) or SR12813 (1 μmol/L) for 24 h, using DMSO as the negative control. HepG2 cells were infected with constitutively activated PXR adenovirus (VP-PXR) for 36 h, with the cells infected with Mock as the negative control. The mRNA levels of PDCD2, PDCD4, PDCD5, and PDCD6 and the expression of miRNA21 were detected using qRT-PCR, and the protein level of PDCD4 was detected with Western blotting. Bioinformatic analysis was performed to predict the potential PXRresponsive elements (PXREs) motifs in the promotor region of human PDCD4.

RESULTS

The expressions of PDCD5 and PDCD6 mRNA did not differ significantly between rifampicin-treated and the control cells, while PDCD4 mRNA expression increased (t=4.209, P=0.008) and PDCD2 mRNA decreased significantly (t=-2.875, P=0.017) in rifampicin-treated cells. The mRNA expressions of PDCD2, PDCD5 and PDCD6 showed no significant difference between SR12813-treated cells and the control cells, while PDCD4 mRNA expression increased obviously in SR12813-treated cells (t=4.574, P=0.006). The PXR target gene MDR1 also increased significantly in the rifampicin- and SR12813-treated cells compared with the control cells (P=0.020 and 0.01, respectively). Infection of the cells with VP-PXR adenovirus resulted in significantly increased expression of PDCD4 and MDR1 mRNA as compared with Mock group (t=3.343, P=0.000; t=3.343, P=0.024, respectively) without causing obvious changes in PDCD2 and PDCD6 mRNA expressions. The protein level of PDCD4 increased significantly in both rifampicin (t= 2.779, P=0.025) group and VP- PXR group (t=3.066, P=0.012). The expression of miRNA21, the negative regulatory factor of PDCD4, did not differ significantly between PXR agonist group and the control group. Informatic analysis revealed the presence of putative PXREs in the 5'-flanking region of PDCD4 gene.

CONCLUSIONS

Our findings demonstrate that PXR agonism in HepG2 cells increases the expression of PDCD4, which is independent of miRNA21 pathway, and PDCD4 may be a target gene of PXR in HepG2 cells.

Critical Role of microRNA-21 in the Pathogenesis of Liver Diseases

MicroRNAs are small non-coding RNAs that range in length from 18 to 24 nucleotides. As one of the most extensively studied microRNAs, microRNA-21 (miR-21) is highly expressed in many mammalian cell types. It regulates multiple biological functions such as proliferation, differentiation, migration, and apoptosis. In this review, we summarized the mechanism of miR-21 in the pathogenesis of various liver diseases. While it is clear that miR-21 plays an important role in different types of liver diseases, its use as a diagnostic marker for specific liver disease or its therapeutic implication are not ready for prime time due to significant variability and heterogeneity in the expression of miR-21 in different types of liver diseases depending on the studies. Additional studies to further define miR-21 functions and its mechanism in association with each type of chronic liver diseases are needed before we can translate the bedside observations into clinical settings.

Long non-coding RNA F11-AS1 inhibits HBV-related hepatocellular carcinoma progression by regulating NR1I3 via binding to microRNA-211-5p

Long non-coding RNAs (lncRNAs) could regulate growth and metastasis of hepatocellular carcinoma (HCC). In this study, we aimed to investigate the mechanism of lncRNA F11-AS1 in hepatitis B virus (HBV)-related HCC. The relation of lncRNA F11-AS1 expression in HBV-related HCC tissues to prognosis was analysed in silico. Stably HBV-expressing HepG2.2.15 cells were established to explore the regulation of lncRNA F11-AS1 by HBx protein, as well as to study the effects of overexpressed lncRNA F11-AS1 on proliferation, migration, invasion and apoptosis in vitro. Subsequently, the underlying interactions and roles of lncRNA F11-AS1/miR-211-5p/NR1I3 axis in HBV-related HCC were investigated. Additionally, the influence of lncRNA F11-AS1 and miR-211-5p on tumour growth and metastasis capacity of HepG2.2.15 cells were studied on tumour-bearing nude mice. Poor expression of lncRNA F11-AS1 was correlated with poor prognosis in patients with HBV-related HCC, and its down-regulation was caused by the HBx protein. lncRNA F11-AS1 was proved to up-regulate the NR1I3 expression by binding to miR-211-5p. Overexpression of lncRNA F11-AS1 reduced the proliferation, migration and invasion, yet induced apoptosis of HepG2.2.15 cells in vitro, which could be abolished by overexpression of miR-211-5p. Additionally, either lncRNA F11-AS1 overexpression or miR-211-5p inhibition attenuated the tumour growth and metastasis capacity of HepG2.2.15 cells in vivo. Collectively, lncRNA F11-AS1 acted as a modulator of miR-211-5p to positively regulate the expression of NR1I3, and the lncRNA F11-AS1/miR-211-5p/NR1I3 axis participated in HBV-related HCC progression via interference with the cellular physiology of HCC.

The Regulatory Role of MicroRNA in Hepatitis-B Virus-Associated Hepatocellular Carcinoma (HBV-HCC) Pathogenesis

The incidence and mortality of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HBV-HCC) is an intractable public health problem in developing countries that is compounded by limited early detection and therapeutic options. Despite the early promise of utilizing the regulatory role of miRNA in liver cancer, this field remains largely in the work-in-progress phase. This exploratory review paper adopts a broad focus in order to collate evidence of the regulatory role of miRNA in each stage of the HBV-HCC continuum. This includes the regulatory role of miRNA in early HBV infection, chronic inflammation, fibrosis/cirrhosis, and the onset of HCC. The paper specifically investigates HBV dysregulated miRNA that influence the expression of the host/HBV genome in HBV-HCC pathogenesis and fully acknowledges that this does not cover the full spectrum of dysregulated miRNA. The sheer number of dysregulated miRNA in each phase support a hypothesis that future therapeutic interventions will need to consider incorporating multiple miRNA panels.

Serum miR-21 correlates with the histological stage of chronic hepatitis B-associated liver fibrosis

This study aimed to investigate the correlation between serum microRNA levels and histological stages of liver fibrosis in patients with chronic hepatitis B (CHB). A total of 28 patients with CHB who received liver biopsy at China Medical University Hospital between October 2012 and April 2013 were included in the study. The patients were divided into four groups according to the histological stages of liver fibrosis by using the METAVIR score. Serum microRNA levels were tested using quantitative real-time PCR after microRNA extraction from patients' serum. Of all the tested microRNAs, miR-21, miR-29, and miR-221 were expressed in the serum. The expression levels of serum miR-21 were significantly correlated with liver fibrosis stages (r = 0.420, P = 0.026). The expression levels of serum miR-21 were significantly correlated with cirrhosis (METAVIR F4 vs. F1-F3, r = 0.386, P = 0.043). The grades of serum miR-21 showed significant ordered differences among different stages of liver fibrosis (P = 0.019). However, miR-21 exhibited an inferior predictive performance for liver fibrosis F2-F4 (AUROC = 0.69) compared with other noninvasive markers of liver fibrosis, namely the aspartate aminotransferase (AST) to platelet ratio index (APRI) and Fibrosis-4 (FIB-4) score (AUROC = 0.83 and 0.86, respectively). Serum miR-21 correlated with the histological stage of liver fibrosis in patients with CHB. The predictive performance of serum miR-21 for the histological stage of liver fibrosis tended to be inferior to those of the APRI and FIB-4 score.

Interplay of Wnt β-catenin pathway and miRNAs in HBV pathogenesis leading to HCC

The prevalence of Hepatocellular carcinoma (HCC) has been identified world-wide. Plethora of factors including chronic infection of HBV/HCV has been characterized for the development of HCC. Although the onset and progression of HCC has been linked with awry of various signaling pathways but precise mechanism, still lies under the multitude layers of curiosity. HBV is spreading with insane speed throughout the world and has been found a main culprit in HCC development after regulating the several cellular pathways including Wnt/β-catenin, Raf/MAPK, Akt and affecting cell multiplication to genomic instability. The role of Wnt/FZD/β-catenin signaling pathway is centralized in liver functions and its anomalous activation leads to HCC development. β-catenin mainly plays a pivotal role in canonical pathway of the system. Altered mainly overexpression of β-catenin along its nuclear localization tunes the aberrations in liver functions and set disease progression. In the development of HCC, modulation of Wnt/FZD/β-catenin signaling pathway by HBV has been established. As HBV infects the cell it affects the miRNAs, the master regulators of cell. Previous studies showed the connection between HBV and cellular miRNAs. In the present review, we unveiled how HBV is deciphering the cellular miRNAs like miR-26a, miR-15a, miR-16-1, miR-148a, miR-132, miR-122, miR-34a, miR-21, miR-29a, miR-222 and miR-199a/b-3p to modulate the Wnt/FZD/β-catenin signaling pathway and develop HCC. These HBV mediated miRNAs may prove future therapeutic options to treat HBV-Wnt/FZD/β-catenin associated HCC.

Dicer1 facilitates liver regeneration in a manner dependent on the inhibitory effect of miR-21 on Pten and Rhob expression

AIMS

Tamoxifen-induced liver-specific Dicer1 deletion (iDicer1^-/-) in mature mice may provide clues demonstrating the genuine effects of acute loss of Dicer1 and miRNAs in the liver regeneration process.

MAIN METHODS

In this study, mice with tamoxifen-induced Dicer1 deletion through the Cre/LoxP system were constructed and then underwent classic 70% partial hepatectomy or CCl4-induced liver injury. To rescue the inhibitory effect of Dicer1 ablation on liver regeneration, miR-21 agomir was injected into the tail vein of iDicer1^-/- mice.

KEY FINDINGS

Unlike constitutive embryonic deletion of Dicer1, tamoxifen-induced Dicer1 deletion did not result in severe liver injury or lesions, providing an ideal model for investigating acute loss of Dicer1 and miRNAs in liver regeneration. Dicer1 deletion led to impaired liver regeneration through the inhibitory effect of miR-21 on PTEN and Rhob expression.

SIGNIFICANCE

In our previous study, we found that embryonic loss of Dicer1 impairs hepatocyte survival and leads to chronic inflammation and progenitor cell activation, while the role of Dicer1 in liver regeneration remains largely unknown. We clearly identified the promotion effect of Dicer1 on liver regeneration by increasing miR-21 expression, which inhibits the expression of two negative cell proliferation regulators, Pten and Rhob.

Activation of the oncogenic miR-21-5p promotes HCV replication and steatosis induced by the viral core 3a protein

BACKGROUND & AIMS

miR-21-5p is a potent oncogenic microRNA targeting many key tumour suppressors including phosphatase and tensin homolog (PTEN). We recently identified PTEN as a key factor modulated by hepatitis C virus (HCV) to promote virion egress. In hepatocytes, expression of HCV-3a core protein was sufficient to downregulate PTEN and to trigger lipid droplet accumulation. Here, we investigated whether HCV controls PTEN expression through miR-21-5p-dependent mechanisms to trigger steatosis in hepatocytes and to promote HCV life cycle.

METHODS

MiR-21-5p expression in HCV-infected patients was evaluated by transcriptome meta-analysis. HCV replication and viral particle production were investigated in Jc1-infected Huh-7 cells after miR-21-5p inhibition. PTEN expression and steatosis were assessed in HCV-3a core protein-expressing Huh-7 cells and in mouse primary hepatocytes having miR-21-5p inhibited or genetically deleted respectively. HCV-3a core-induced steatosis was assessed in vivo in Mir21a knockout mice.

RESULTS

MiR-21-5p expression was significantly increased in hepatic tissues from HCV-infected patients. Infection by HCV-Jc1, or transduction with HCV-3a core, upregulated miR-21-5p expression and/or activity in Huh-7 cells. miR-21-5p inhibition decreased HCV replication and release of infectious virions by Huh-7 cells. HCV-3a core-induced PTEN downregulation and steatosis were further prevented in Huh-7 cells following miR-21-5p inhibition or in Mir21a knockout mouse primary hepatocytes. Finally, steatosis induction by AAV8-mediated HCV-3a core expression was reduced in vivo in Mir21a knockout mice.

CONCLUSION

MiR-21-5p activation by HCV is a key molecular step, promoting both HCV life cycle and HCV-3a core-induced steatosis and may be among the molecular changes induced by HCV-3a to promote carcinogenesis.

A novel HBx genotype serves as a preoperative predictor and fails to activate the JAK1/STATs pathway in hepatocellular carcinoma

BACKGROUND & AIMS

Genetic variability in the hepatitis B virus X gene (HBx) is frequently observed and is associated with hepatocellular carcinoma (HCC) progression. However, a genotype classification based on the full-length HBx sequence and the impact of genotypes on hepatitis B virus (HBV)-related HCC prognosis remain unclear. We therefore aimed to perform this genotype classification and assess its clinical impact.

METHODS

We classified the genotypes of the full-length HBx gene through sequencing and a cluster analysis of HBx DNA from a cohort of patients with HBV-related HCC, which served as the primary cohort (n = 284). Two independent HBV-related HCC cohorts, a validation cohort (n = 171) and a serum cohort (n = 168), were used to verify the results. Protein microarray assay analysis was performed to explore the underlying mechanism.

RESULTS

In the primary cohort, the HBx DNA was classified into 3 genotypes: HBx-EHBH1, HBx-EHBH2, and HBx-EHBH3. HBx-EHBH2 (HBx-E2) indicated better recurrence-free survival and overall survival for patients with HCC. HBx-E2 was significantly correlated with the absence of liver cirrhosis, a small tumor size, a solitary tumor, complete encapsulation and Barcelona Clinic Liver Cancer (BCLC) stage A-0 tumors. Additionally, HBx-E2 served as a significant prognostic factor for patients with BCLC stage B HCC after hepatectomy. Mechanistically, HBx-E2 is unable to promote proliferation in HCC cells and normal hepatocytes. It also fails to activate the Janus kinase 1 (JAK1)/signal transducer and activator of transcription 3 (STAT3)/STAT5 pathway.

CONCLUSION

Our study identifies a novel HBx genotype that is unable to promote the proliferation of HCC cells and suggests a potential marker to preoperatively predict the prognosis of patients with BCLC stage B, HBV-associated, HCC.

LAY SUMMARY

We classified a novel genotype of the full-length hepatitis B virus X gene (HBx), HBx-E2. This genotype was identified in tumor and nontumor tissues from patients with hepatitis B virus-related hepatocellular carcinoma. HBx-E2 could preoperatively predict the prognosis of patients with intermediate stage hepatocellular carcinoma, after resection.

Viral modulation of cellular RNA alternative splicing: A new key player in virus-host interactions?

Upon viral infection, a tug of war is triggered between host cells and viruses to maintain/gain control of vital cellular functions, the result of which will ultimately dictate the fate of the host cell. Among these essential cellular functions, alternative splicing (AS) is an important RNA maturation step that allows exons, or parts of exons, and introns to be retained in mature transcripts, thereby expanding proteome diversity and function. AS is widespread in higher eukaryotes, as it is estimated that nearly all genes in humans are alternatively spliced. Recent evidence has shown that upon infection by numerous viruses, the AS landscape of host‐cells is affected. In this review, we summarize recent advances in our understanding of how virus infection impacts the AS of cellular transcripts. We also present various molecular mechanisms allowing viruses to modulate cellular AS. Finally, the functional consequences of these changes in the RNA splicing signatures during virus–host interactions are discussed.

This article is categorized under:

RNA in Disease and Development > RNA in Disease

RNA Processing > Splicing Regulation/Alternative Splicing

microRNAs: Key players in virus-associated hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is known as one of the major health problems worldwide. Pathological analysis indicated that a variety of risk factors including genetical (i.e., alteration of tumor suppressors and oncogenes) and environmental factors (i.e., viruses) are involved in beginning and development of HCC. The understanding of these risk factors could guide scientists and clinicians to design effective therapeutic options in HCC treatment. Various viruses such as hepatitis B virus (HBV) and hepatitis C virus (HCV) via targeting several cellular and molecular pathways involved in HCC pathogenesis. Among various cellular and molecular targets, microRNAs (miRNAs) have appeared as key players in HCC progression. miRNAs are short noncoding RNAs which could play important roles as oncogenes or tumor suppressors in several malignancies such as HCC. Deregulation of many miRNAs (i.e., miR-222, miR-25, miR-92a, miR-1, let-7f, and miR-21) could be associated with different stages of HCC. Besides miRNAs, exosomes are other particles which are involved in HCC pathogenesis via targeting different cargos, such as DNAs, RNAs, miRNAs, and proteins. In this review, we summarize the current knowledge of the role of miRNAs and exosomes as important players in HCC pathogenesis. Moreover, we highlighted HCV- and HBV-related miRNAs which led to HCC progression.

Exosomes derived from HBV-associated liver cancer promote chemoresistance by upregulating chaperone-mediated autophagy

Liver cancer, which is the second leading cause of tumor-associated mortality, is of great concern worldwide due to its resistance to chemotherapeutic drugs. Transcatheter arterial chemoembolization (TACE) has previously been used as a treatment for unresectable liver tumors in China; however, the response to TACE treatment differs between patients. It has been reported that hepatitis B virus (HBV)-as sociated tumors are less sensitive to TACE treatment compared with non-HBV-associated liver cancer. Previous studies have demonstrated that exosomes serve a crucial role in hepatic carcinoma chemoresistance. We therefore hypothesized that HBV may modulate chemosensitivity via exosomes. The aim of the present study was to investigate how exosomes affect chemoresistance by assessing their role in chaperone-mediated autophagy (CMA)-dependent chemoresistance in HBV-associated liver cancer. Iconography data from HBV-positive and HBV-negative patients with hepatic carcinoma receiving TACE treatment were assessed, and it was revealed that the tumor volume was decreased in the patients with non-HBV-associated liver cancer compared with that in the patients with HBV-associated tumors following TACE therapy. Furthermore, it was revealed that exosomes from HBV-infected liver cancer cells were able to downregulate cell apoptosis when treated with oxaliplatin compared with exosomes from normal HepG2 cells. Furthermore, the results demonstrated that HBV-associated exosomes modulate cell death via activating the CMA pathway, and its key molecule, lysosome-associated membrane protein (Lamp2a), was also upregulated. Lamp2a-knockdown was also found to reverse anti-apoptotic effects in liver cancer. Taken together, the results of the present study suggest that chemoresistance in patients with HBV-associated hepatic tumors may be mediated by exosomes, and thus may provide a basis for the development of novel treatment strategies for chemoresistant liver cancer.

Aberrant DNA methylation profile of hepatitis B virus infection

We aimed to study the aberrant DNA methylation profile associated with hepatitis B virus (HBV) infection and, to identify key genes and pathways associated with the HBV infection stage. A total of 54 antiviral treatment-naïve HBV-infected patients and six healthy controls were included. Genome-wide methylated DNA immunoprecipitation analysis was performed, as previously described, after which the chip data were preprocessed. Subsequently, Cytoscape software was used for the construction of a protein-protein interaction network, and a database for annotation, visualization, and integrated discovery software was used to conduct functional enrichment analysis. A total of 711 794 CpGs were obtained after data quality control, among which 152 780, 113 814, 90 747, and 175 868 CpGs showed differential methylation in acute hepatitis B (AHB) vs control, total-C vs control, CH1 vs CA1, and AHB vs total-C, respectively. Furthermore, RIPK3, PRDM10, JUN, and SNAI1 were at the center of the four associated networks, respectively. Differential methylated genes differentially methylated in these four comparisons were significantly enriched with olfactory transduction; positive regulation of transport; negative regulation of protein amino acid phosphorylation (eg, JUN), phosphorylation, phosphorus metabolic process, and phosphate metabolic process; and programmed cell death, respectively. RIPK3, PRDM10, JUN, and SNAI1 as well as olfactory transduction, positive regulation of transport, negative regulation of phosphorylation, and programmed cell death are important for the transformation associated with HBV infection stage. Moreover, JUN may be involved in HBV infection, mainly via the negative regulation of amino acid phosphorylation.

Let-7g affects cell proliferation, migration and invasion in cervical squamous cell carcinomas via targeting collagen I

Cervical cancer is one of the most common types of malignant gynecological tumors worldwide. Let-7g and collagen I have been reported to be involved in the occurrence and development of various cancers, but the clinical significance and biological function of these proteins in cervical squamous cell carcinoma (CSCC) have not been reported. Therefore, this study aimed to determine the underlying roles of let-7g and collagen I in CSCC. Tissue chip, qRT-PCR and western blot assays were used to examine the expression of collagen I in CSCC patients. A dual-luciferase reporter system was used to demonstrate the interaction between let-7g and collagen I. CCK8 and Transwell assays were applied to examine the effects of let-7g and collagen I on cell proliferation, migration and invasion. The results showed that collagen I was obviously increased in CSCC patients. Moreover, it was confirmed that collagen I is the direct target of let-7g. Gain- and loss-of-function experiments, for let-7g and collagen I indicated that let-7g obviously inhibited the proliferation, migration and invasion abilities of CSCC by regulating collagen I. Collectively, these data suggest that let-7g suppresses tumor growth and metastasis by targeting collagen I; therefore, let-7g and collagen I can be considered novel potential therapeutic targets for CSCC.

MicroRNA-21 down-regulates inflammation and inhibits periodontitis

Periodontitis is one of the most prevalent inflammatory diseases, characterized by gingival inflammation and alveolar bone loss. MicroRNAs (MiRNAs) are important regulators of inflammation and involved in periodontitis pathogenesis. In this work, we studied the roles of microRNA-21 (miR-21) in periodontitis. MiR-21 is up-regulated in both periodontitis patients and the mice that induced with periodontitis. We tested the roles of miR-21 in the macrophages challenged by periodontitis pathogen Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS). MiR-21 expression is up-regulated in P. gingivalis LPS-stimulated macrophages. MiR-21 mimic inhibits the pro-inflammatory cytokine production by macrophages, while miR-21 deficiency elevates the production of pro-inflammatory cytokines. Moreover, absence of miR-21 promotes activation of nuclear factor-κB (NF-κB) in P. gingivalis LPS- stimulated cells. In a murine periodontitis model, ligation induced exacerbated gingival inflammation and alveolar bone loss in miR-21 deficient mice than their wild-type littermates. These results demonstrated the anti-inflammatory function of miR-21 in vitro and in vivo, indicating miR-21 could be an interventional target for the control of periodontitis.

Colorimetric PCR-Based microRNA Detection Method Based on Small Organic Dye and Single Enzyme

microRNAs (miRNAs) have been a class of promising disease diagnostic biomarkers and therapeutic targets for their important biological functions. However, because of the high homology, interference from precursors (pri-miRNA, pre-miRNA), as well as limitations in the current assay technologies, it poses high demand and challenge for a specific, efficient, and economic miRNA assay method. Here, we propose a new miRNA detection method based on a label-free probe and a small organic dye with sequence dependence, realizing the sequence-specific and colorimetric detection of target miRNA. What is pleasantly surprising, only one enzyme is enough to propel the whole miRNA assay process, greatly simplifying the reaction component and detection process. Together with PCR amplification for the high enough sensitivity and three checks for specificity control, a detection limit of 5 fM was obtained and even one mutation could be discriminated visually. Overall, the new method makes much progress in convenience and economy of PCR-based miRNA assay method so that miRNA assay is going to be more friendly and affordable.

miR-21-3p Regulates Influenza A Virus Replication by Targeting Histone Deacetylase-8

Influenza A virus (IAV) is responsible for severe morbidity and mortality in animals and humans worldwide. miRNAs are a class of small noncoding single-stranded RNA molecules that can negatively regulate gene expression and play important roles in virus-host interaction. However, the roles of miRNAs in IAV infection are still not fully understood. Here, we profiled the cellular miRNAs of A549 cells infected with A/goose/Jilin/hb/2003 (H5N1) and a comparison A/Beijing/501/2009 (H1N1). miRNA microarray and quantitative PCR analysis showed that several miRNAs were differentially expressed in A549 cells during IAV infection. Subsequently, we demonstrated that IAV replication was essential for the regulation of these miRNAs, and bioinformatic analysis revealed that the targets of these miRNAs affected biological processes relevant to IAV replication. Specifically, miR-21-3p was found to be down-regulated in IAV-infected A549 cells and selected for further detailed analysis. Target prediction and functional study illustrated that miR-21-3p repressed the expression of HDAC8 by targeting its 3′UTR. Furthermore, we confirmed miR-21-3p could promote virus replication, which was similar to the result of knocking down HDAC8, indicating that miR-21-3p promoted IAV replication by suppressing HDAC8 expression. Altogether, our results suggest a potential host defense against IAV through down-regulation of miR-21-3p.

LncRNA HOXA11-AS promotes hepatocellular carcinoma progression by repressing miR-214-3p

Accumulating studies supported that lncRNAs played important roles in tumorigenesis. LncRNA HOXA11‐AS was a novel lncRNA that has been proved to involved in several tumours. However, the role of HOXA11‐AS in the development of hepatocellular carcinoma (HCC) remains to be explained. In our study, we showed that HOXA11‐AS expression was up‐regulated in the HCC tissues, and the higher expression of HOXA11‐AS was associated with the advanced stage in the HCC samples. In addition, we indicated that the expression of HOXA11‐AS was up‐regulated in HCC cell lines (Hep3B, SMMC‐7721, MHCC97‐H and BEL‐7402) compared with normal liver cell lines (HL‐7702). Overexpression of HOXA11‐AS promoted HCC proliferation and invasion and induced the epithelial‐mesenchymal transition (EMT) and knockdown of HOXA11‐AS suppressed the HCC cell proliferation and invasion. However, we showed that miR‐214‐3p expression was down‐regulated in the HCC tissues and cell lines. Ectopic expression of miR‐214‐3p suppressed HCC cell proliferation and invasion. Furthermore, we indicated that overexpression of HOXA11‐AS decreased the miR‐214‐3p expression and the expression of miR‐214‐3p was negatively related with the HOXA11‐AS expression in HCC samples. Ectopic expression of HOXA11‐AS increased HCC proliferation and invasion and induced EMT through inhibiting miR‐214‐3p expression. These data suggested that HOXA11‐AS/miR‐214‐3p axis was responsible for development of HCC.

CD38/cADPR Signaling Pathway in Airway Disease: Regulatory Mechanisms

Asthma is an inflammatory disease in which proinflammatory cytokines have a role in inducing abnormalities of airway smooth muscle function and in the development of airway hyperresponsiveness. Inflammatory cytokines alter calcium (Ca²⁺) signaling and contractility of airway smooth muscle, which results in nonspecific airway hyperresponsiveness to agonists. In this context, Ca²⁺ regulatory mechanisms in airway smooth muscle and changes in these regulatory mechanisms encompass a major component of airway hyperresponsiveness. Although dynamic Ca²⁺ regulation is complex, phospholipase C/inositol tris-phosphate (PLC/IP3) and CD38-cyclic ADP-ribose (CD38/cADPR) are two major pathways mediating agonist-induced Ca²⁺ regulation in airway smooth muscle. Altered CD38 expression or enhanced cyclic ADP-ribosyl cyclase activity associated with CD38 contributes to human pathologies such as asthma, neoplasia, and neuroimmune diseases. This review is focused on investigations on the role of CD38-cyclic ADP-ribose signaling in airway smooth muscle in the context of transcriptional and posttranscriptional regulation of CD38 expression. The specific roles of transcription factors NF-kB and AP-1 in the transcriptional regulation of CD38 expression and of miRNAs miR-140-3p and miR-708 in the posttranscriptional regulation and the underlying mechanisms of such regulation are discussed.

HBeAg-induced miR-106b promotes cell growth by targeting the retinoblastoma gene

Chronic HBV infection is a major cause of hepatocellular carcinoma (HCC). The association between hepatitis B "e" antigen (HBeAg) and HCC is well-established by epidemiological studies. Nonetheless, the biological role of HBeAg in HCC remains enigmatic. We investigate the role of HBeAg in HBV-related HCC. Our findings suggest that HBeAg enhances cell proliferation and accelerates progression from G0/G1 phase to the S phase of the cell cycle in Huh7 cells. Examination of host gene expression and miRNA expression profiles reveals a total of 21 host genes and 12 host miRNAs that were differentially regulated in cells expressing HBeAg. Importantly, HBeAg induced the expression of miR-106b, an oncogenic miRNA. Interestingly, HBeAg-expression results in a significant reduction in the expression of retinoblastoma (Rb) gene, an experimentally validated target of miR-106b. Inhibition of miR-106b significantly increased the expression of the Rb gene, resulting in reduced cell proliferation and slowing of cell cycle progression from the G0/G1 phase to S phase. These observations suggest that the up-regulation of miR-106b by HBeAg contributes to the pathogenesis of HBV-related HCC by down-regulating the Rb gene. Our results highlight a role for HBeAg in HCC and provide a novel perspective on the molecular mechanisms underlying HBV-related HCC.

Expression Profiling of Cellular MicroRNA in Asymptomatic HBsAg Carriers and Chronic Hepatitis B Patients

Background

MicroRNAs (miRNAs) may serve as potential molecular markers to predict liver injury resulting from chronic hepatitis B (CHB). In the present study, we want to study the expression profile and clinical significance of miRNAs at different stages of CHB virus infection.

Methods

Using miRNA microarray, we investigated the global expression profiles of cellular miRNA in asymptomatic hepatitis B antigen carriers (ASCs) and CHB patients, compared with healthy controls (HCs).

Results

We identified 79 and 203 differentially expressed miRNAs in the peripheral blood mononuclear cells of ASCs and CHB patients compared to HCs, respectively. Some of these miRNAs were common to ASCs and CHB patients, but another set of miRNAs that showed differential expression between ASCs and CHB patients was also identified. Gene ontology and pathway enrichment analysis showed that the target genes of the identified miRNAs played a role in important biological functions, such as learning or memory, cell-cell adherens junction, ion channel inhibitor activity, TGF-beta signaling pathway, and p53 signaling pathway.

Conclusion

We identified some significant differentially expressed miRNA in different phases of HBV infection, which might serve as biomarkers or therapeutic targets in the future.

miRNA signatures can predict acute liver failure in hepatitis E infected pregnant females

Background

Acute viral hepatitis E (AVH-E) can often result in acute liver failure (ALF) during pregnancy. microRNAs serve as mediators in drug induced liver failure. We investigated their role as a biomarker in predicting ALF due to HEV (ALF-E).

Methods

We performed next generation sequencing and subsequent validation studies in PBMCs of pregnant (P) self limiting AVH-E, ALF due to HEV (ALF-E) and compared with AVH-E in non-pregnant (NP) females and healthy controls.

Findings

Eleven microRNAs were significantly expressed in response to HEV infection; importantly, miR- 431, 654, 1468 and 4435, were distinctly expressed in pregnant self-limiting AVH-E and healthy females (p = 0.0005), but not in ALF-E. Sixteen exclusive microRNAs differentiated ALF-E from self limiting AVH-E in pregnant females. miR-450b which affects cellular proliferation and metabolic processes through RNF20 and SECB was predominanlty upregulated and correlated with poor outcome (ROC 0.958, p = 0.001).

Interpretation

Our results reveal that a specific microRNA profile can predict fatality in ALF-E in pregnancy. These microRNAs could be exploited as prognostic biomarkers and help in the development of new therapeutic interventions.

Dynamic microRNAome profiles in the developing porcine liver

Increasing evidence suggests that micro (mi)RNAs play important roles in various biological process. To evaluate the roles of miRNA in the porcine liver, we investigated the dynamic profiles of microRNAomes using liver tissue from pigs during the embryonic period (embryonic day 90), weaning stage (postnatal day 30), and adult stage (7 years old). A total of 186 unique miRNAs were differentially expressed during liver development. We also identified that 17, 13, and 6 miRNAs were specifically abundant at embryonic day 90, postnatal day 30, and at 7 years, respectively. Besides regulating basic cellular roles in development, miRNAs expressed at the three developmental stages also participated in regulating “embryonic liver development,” “early hepatic growth and generating a functioning liver,” and “energy metabolic processes,” respectively. Our study indicates that miRNAs are extensively involved in liver development, and provides a valuable resource for the further elucidation of miRNA regulatory roles during liver development.

The role of microRNAs in hepatocyte metabolism and hepatitis B virus replication

Though efficient vaccines against hepatitis B virus (HBV) and antiviral therapies are available, chronic HBV infection is still a global health problem. The process of HBV infection and HBV life cycle are extensively studied in last decades, however, the mechanisms of HBV-induced alterations of host cell metabolisms and host factors involved in modulating of viral replication are not fully understood. Thus, it is an important issue to examine these specific HBV-host interactions for development of novel strategies for antiviral therapies. Recently, microRNAs (miRNAs), a class of post-transcriptional regulatory small RNA, seem to be the relevant fine tuning factors of various cellular activities and pathways, including cell growth, metabolism, and viral replication. In this review, we summarize the up to date knowledge concerning the virus-host interactions and emphasizing on the role of miRNAs in regulation of HBV replication and host cell metabolism.

Humic acid inhibits HBV-induced autophagosome formation and induces apoptosis in HBV-transfected Hep G2 cells

Hepatitis B Virus (HBV) utilizes several mechanisms to survive in the host cells and one of the main pathways being autophagosome formation. Humic acid (HA), one of the major components of Mineral pitch, is an Ayurvedic medicinal food, commonly used by the people of the Himalayan regions of Nepal and India for various body ailments. We hypothesized that HA could induce cell death and inhibit HBV-induced autophagy in hepatic cells. Incubation of Hep G2.2.1.5 cells (HepG2 cells stably expressing HBV) with HA (100 μM) inhibited both cell proliferation and autophagosome formation significantly, while apoptosis induction was enhanced. Western blot results showed that HA incubation resulted in decreased levels of beclin-1, SIRT-1 and c-myc, while caspase-3 and β-catenin expression were up-regulated. Western blot results showed that HA significantly inhibited the expression of HBx (3-fold with 50 μM and 5-fold with 100 μM) compared to control cells. When HA was incubated with HBx-transfected Hep G2 cells, HBx-induced autophagosome formation and beclin-1 levels were decreased. These data showed that HA induced apoptosis and inhibited HBV-induced autophagosome formation and proliferation in hepatoma cells.

Trimetazidine protects against cardiac ischemia/reperfusion injury via effects on cardiac miRNA‑21 expression, Akt and the Bcl‑2/Bax pathway

Trimetazidine is a piperazine-derived metabolic agent, which exerts cell protective effects and has been reported to be efficient in the treatment of chronic stable angina pectoris. In addition, it has been shown to exert protection against acute myocardial infarction. The present study aimed to investigate whether trimetazidine protects against cardiac ischemia/reperfusion (I/R) injury, and to determine whether its curative effects are associated with microRNA (miRNA)-21 expression, Akt, and the B-cell lymphoma 2 (Bcl-2)/Bcl-2-associated X protein (Bax) pathway. Cardiac I/R injury was induced by ligating the left anterior descending coronary artery in adult rats. Subsequently, cardiac function was evaluated, and the expression levels of miRNA-21, Bcl-2, Bax and phosphorylated-Akt were detected using quantitative polymerase chain reaction and western blotting. The results indicated that trimetazidine was able to significantly protect cardiac function and reduce infarct size in rats following cardiac I/R injury. Furthermore, trimetazidine significantly promoted miRNA-21 expression and phosphorylated-Akt protein expression, and reduced the Bcl-2/Bax ratio in rats following cardiac I/R injury. Knockdown of miRNA-21 using anti-miR-21 plasmids was able to reverse the protective effects of trimetazidine against cardiac I/R injury. These results indicated that miRNA-21 serves a protective role in cardiac I/R injury via Akt and the Bcl-2/Bax pathway. In addition, trimetazidine exerts protective effects against cardiac I/R injury through cardiac miRNA-21 expression, Akt, and the Bcl-2/Bax pathway. Therefore, the present study provided evidence regarding the protective effects of miRNA-21 on cardiac I/R injury following treatment with trimetazidine in vivo.

MicroRNA-21 regulates the ERK/NF-κB signaling pathway to affect the proliferation, migration, and apoptosis of human melanoma A375 cells by targeting SPRY1, PDCD4, and PTEN

This study aims to explore the effects of microRNA-21 (miR-21) and ERK/NF-κB signaling pathway on human melanoma A375 cells. The melanoma tissues and adjacent normal tissues were obtained from 45 melanoma patients. qRT-PCR was conducted to quantify the expression of miR-21 and the gene mRNA expressions. Human melanoma A375 cells were divided into the Mock, negative control (NC), miR-21 inhibitors, miR-21 inhibitors + siRNA-SPRY1, miR-21 inhibitors + siRNA-PDCD4, and miR-21 inhibitors + siRNA-PTEN groups. Western blotting was used to determine protein expressions. CCK8 assay and Transwell assay were performed to evaluate the proliferation, migration, and invasion of A375 cells. Annexin V/propidium iodide double staining was adopted to detect cell apoptosis. MiR-21 expression was higher in melanoma tissues than in adjacent tissues, while the mRNA and protein expressions of SPRY1, PDCD4, and PTEN were lower in melanoma tissues than in adjacent tissues. Compared with the Mock and NC groups, the miR-21 inhibitors group exhibited increased expressions of SPRY1, PDCD4, and PTEN and decreased expressions of ERK, p-ERK, NF-κB p65, and p-NF-κB p65. After transfection of miR-21 inhibitors, the proliferation, migration, and invasion of A375 cells were inhibited, while the apoptosis of A375 cells was promoted. However, the effects of miR-21 inhibitors on the growth, migration, invasion, and apoptosis of A375 cells were reversed after transfection of siRNA-SPRY1, siRNA-PDCD4, or siRNA-PTEN. MiR-21 can promote the proliferation, migration, and inhibit the apoptosis of human melanoma A375 cells by inhibiting SPRY1, PDCD4, and PTEN via ERK/NF-κB signaling pathway. © 2016 Wiley Periodicals, Inc.

HBx-induced miR-21 suppresses cell apoptosis in hepatocellular carcinoma by targeting interleukin-12

Hepatitis B virus (HBV) X protein (HBx) plays a key role in the initiation and progression of HBV infection‑induced hepatocellular carcinoma (HCC). Oncogenic microRNA-21 (miR-21) can be modulated by HBx protein in HCC. However, critical regulator genes in the pathway of HBx-induced miR-21 in HCC remain unclear. This study aimed to investigate the role of HBx-induced miR-21 in the apoptosis of HCC cells. In the study, interleukin-12 (IL-12) was demonstrated as a direct target of miR-21 by dual‑luciferase report assay, and miR-21 was highly expressed in HCC cells (HepG2 and HepG2 2.2.15) compared to L02 cells, but IL-12 was weakly expressed as detected by real-time quantitative PCR (RT-qPCR). Furthermore, miR-21 mimics, inhibitor, HBx-targeted siRNA, and the HBx overexpression vector (pHBx) were used to observe the regulatory effects of HBx-induced miR-21 via IL-12, and cell apoptosis was assessed. The results showed that overexpression of HBx resulted in the inhibition of IL-12. A high level of miR-21 resulted in a significant increase in proliferation and a decrease in IL-12 expression. Inhibition of miR-21 resulted in a significant increase in apoptosis and increased IL-12 expression. The results suggest that HCC cell apoptosis was suppressed at least partially through HBx-induced miR-21 by targeting IL-12.

Hepatitis B Virus X Protein and Hepatocarcinogenesis

Chronic hepatitis B virus (HBV) infection is one of the most associated factors in hepatocarcinogenesis. HBV is able to integrate into the host genome and encode the multi-functional hepatitis B virus x protein (HBx). Although the mechanism between HBx and carcinogenesis is still elusive, recent studies have shown that HBx was able to influence various signaling pathways, as well as epigenetic and genetic processes. This review will examine and summarize recent literature about HBx’s role in these various processes.